Molecular mechanisms underlying the neuroendocrine occurrence and function of neurophysins (NP's) and associated neuropeptide hormones oxytocin and vasopressin have been studied. The NP's neuropeptides are dominant polypeptides of the hypothalamo-neurohypophysial system ("classical" site of occurrence). Their intraneuronal biosynthesis, translocation, and structural transitions from precursors to mature, interacting polypeptides comprise major elements of neurosecretory function. NP and neuropeptide hormone-related polypeptides also have been detected in putative neuromodulator-neurotransmitter pathways within the central nervous system as well as in several peripheral (e.g. endocrine) sites ("non-classical" sites of occurrence). During the current year, a study has been continued of "non-classical" sites of the hormone/NP neuroendocrine system, including the ovary and peripheral neurons. Both hormone- and NP-immunoreactive molecules have been found in the ovary. The results so argue far that the ovary may be a site of local synthesis of both oxytocin-, vasopressin-, and neurophysin-related molecules. The relationships of ovarian molecular species to those produced in the hypothalamo-neurohypophysial pathway are being studied. Some of our recent results suggest that structurally unique neoroendocrine peptides are produced in different pathways. The molecular mechanisms and neuroendocrine peptide function in the ovary, as in many other "non-classical" sites, remains to be defined rigorously. Separately, in hypothesis has been developed and is being examined that biosynthetic precursors of the neurohypophysial hormones have a defined conformational organization and that this organization helps regulate the production of active peptides produced in neuroendocrine pathways which make the precursors. A method was devised to produce biosynthetic precursor, and ultimately sequence modeled and site-specific mutants; a semisynthetic oxytocin/neurophysin precursor analog has been made. An evaluation of structural characteristics of the semisynthetic precursor, and the impact of these characteristics on enzymatic processing reactions, is in progress.